1. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program Light Sensor in Autonomous Mode

2. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program Light Sensor in Autonomous Mode  Performance Objective: Given the components of a VEX robotics design system program a light sensor in autonomous mode to have the robot travel full speed forward when a lot of light is detected, but to move slowly forward when there is little to no light detected.  Enabling Objectives:  explain the purpose of a light sensor  explain how a light sensor operates  draw a flow chart for using a light sensor  program a light sensor

3. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Light sensor  The light sensor enables a robot to detect light  Robots can be programmed to have a specific reaction if a certain amount of light is detected because of the analog input  The light sensor uses a cadmium sulfosolenide (CdS) photoconductive photocell  The CdS photocell is a photo resistor, meaning that its resistance value changes based on the amount of incident light (The direct light that falls on the surface)

4. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Verify the sensor  Plug the sensor into an analog port  Open easyC and download the light sensor test code  Move your hand over the light sensor to see the change in value  The more light there is, the lower the analog value

5. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program the light sensor  Program a VEX robot equipped with a light sensor to move forward quickly when there is a lot of light in the room, and move slowly when there is little or no light in the room  Draw the flow chart of a program that can complete the above task

6. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program the light sensor  Open a new competition project and configure the microcontroller for the light sensor  Add a variable for the light sensor  Insert an appropriate driving mode block into the operator tab

7. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program the light sensor  Insert a while loop where 1==1  Insert the get light sensor value block

8. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program the light sensor  Insert an If statement to move the robot forward at full speed if the light sensor value is less than 50, meaning there is a lot of light

9. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Program the light sensor  Insert an Else-If statement to move the robot forward slowly if there is very little to no light in the room

10. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Test your code  Build and download your code  Run the code with the Competition Switch Simulator  The robot should move forward quickly with the lights on, and move forward slowly when the lights are turned off

11. Available at: www.etcurr.com Lesson 3.5 – Program Light Sensor in Autonomous Mode Show it off!  If your code works, show it to your instructor  If the robot does not run correctly, go back through the lesson and double check your code  For more technical data on the light sensor visit: http://www.vexforum.com/wiki/index.php/Lig ht_Sensor